This specification relates to optical communications. Conventional optical circulators are employed in systems transmitting optical signals in order to transmit optical signals in a particular direction. For example, in a three port optical circulator, an optical signal input at the first port will be transmitted to the second port. An optical signal input at the second port will be transmitted to the third port. However, optical signals typically will not be transmitted in the reverse direction. For example, an optical signal input at the second port will not be transmitted to the first port.